1. Field of the Invention
The present invention relates to a solvent composition useful for a degreasing agent, a defluxing agent, a water-displacement agent or the like which is an agent for removing grease, oil, flux or water attached to an article such as a printed circuit board, an electronic component such as IC, a precision machine part or a glass substrate.
2. Discussion of Background
1,1,2-trichloro-1,2,2-trifluoroethane (hereinafter referred to simply as R113), a solvent mixture composition of this R113 with a solvent soluble therein, or 1,1,1,-trichloroethane, which is excellent in nonflammability, low toxicity and stability, is widely used for various degreasing agents, defluxing agents, etc. R113 has a characteristic such that it selectively dissolves various soils without damaging a precision machine component or a substrate of e.g. metal, plastic or elastomer. Accordingly, it was most suitable for cleaning various electronic components, precision machine parts, optical parts, etc. made of metals, plastics, elastomers, etc.
R113 and 1,1,1-trichloroethane which have been heretofore used, have various merits. However, since they are chemically very stable, they have long atmospheric lifetime and diffuses to the stratosphere, where they will be decomposed by ultraviolet radiation from the sun to release chlorine radicals. Such chlorine radicals will initiate a chain reaction with ozone and deplete the ozone layer. Accordingly, regulations for limiting their production and consumption have been implemented. Therefore, a research has been actively conducted to develop an alternative solvent which scarcely depletes the ozone layer and which is useful as a substitute for conventional R113 or 1,1,1-trichloroethane.
U.S. Pat. No. 5,116,525 discloses azeotropic compositions comprising dichloropentafluoropropane (hereinafter referred to simply as R225), trans-1,2-dichloroethylene (hereinafter referred to simply as t-DE), and methanol (hereinafter referred to simply as MeOH), ethanol (hereinafter referred to simply as EtOH) or isopropanol.
Among them, disclosed as a composition containing MeOH, is an azeotropic composition which comprises from 47 to 57 wt % of R225 comprising from 50 to 75 wt % of 3,3-dichloro-1,1,1,2,2-pentafluoropropane (hereinafter referred to simply as R225ca) and from 25 to 50 wt % of 1,3-dichloro-1,1,2,2,3-pentafluoropropane (hereinafter referred to simply as R225cb), from 38 to 48 wt % of t-DE and from 3 to 9 wt % of MeOH, and which has a boiling point of 43.7xc2x0 C. under atmospheric pressure of 760 mmHg.
However, it has been found by the present inventors that the above azeotropic composition gives a damage to the material of the article to be cleaned and also has inflammability.
It is a first object of the present invention to provide a solvent composition comprising R225, t-DE and MeOH, which satisfies the excellent properties which R113 or 1,1,1-trichloroethane has, which can be used as an alternative solvent which gives little influence to the ozone layer and which presents no influence over the material of an article to be cleaned and has no inflammability.
On the other hand, the above-mentioned patent specification discloses, as a composition containing EtOH, an azeotropic composition which comprises from 47 to 57 wt %, preferably 51.7 wt %, of R225 comprising from 50 to 75 wt % of R225ca and from 25 to 50 wt % of R225cb, from 40 to 50 wt %, preferably from 45.3 wt %, of t-DE, and from 1 to 5 wt %, preferably 3 wt %, of EtOH, and which has a boiling point of 46.5xc2x0 C. under atmospheric pressure of 760 mmHg.
However, it has been found by the present inventors that the above azeotropic composition is not a true azeotropic composition, and it tends to undergo a compositional change.
Accordingly, a second object of the present invention is to provide an azeotropic-like solvent composition having a true composition comprising R225, t-DE and EtOH, which satisfies the excellent properties which R113 or 1,1,1,-triclhoroethane has, which is useful as an alternative solvent which gives little influence to the ozone layer and which undergoes no substantial compositional change.
The present invention provides a solvent composition (hereinafter referred to simply as composition X) comprising (a) R225, (b) t-DE and (c) MeOH, wherein the proportions of (a), (b) and (c) in the total amount of (a), (b) and (c) are from 57 to 75 wt %, from 20 to 35 wt % and from 5 to 8 wt %, respectively.
Further, the present invention provides an azeotropic-like solvent composition (hereinafter referred to simply as composition Y) comprising (a) R225, (b) t-DE and (d) EtOH, wherein the proportions of (a), (b) and (d) in the total amount of (a), (b) and (d) are from 30 to 43 wt %, from 53 to 65 wt % and from 2 to 5 wt %, respectively.
In the present invention, R225 represents one or more of dichloropentafluoropropanes represented by the molecular formula C3HCl2F5. R225 is preferably at least one member selected from the group consisting of R225ca and R225cb. Particularly preferred R225 is a mixture of R225ca and R225cb. The blend ratio is preferably R225ca/R225cb=1 to 99 wt %/1 to 99 wt %, more preferably R225ca/R225cb=40 to 75 wt %/25 to 60 wt %.
Composition X of the present invention comprises (a) R225, (b) t-DE and (c) MeOH, wherein the proportions of (a), (b) and (c) in the total amount of (a), (b) and (c) are from 57 to 75 wt %, from 20 to 35 wt % and from 5 to 8 wt %, respectively. Preferred proportions of (a), (b) and (c) in the total amount of (a), (b) and (c) are from 61 to 67 wt %, from 27 to 32 wt % and from 6 to 7 wt %, respectively.
Whereas, composition Y of the present invention comprises (a) R225, (b) t-DE and (d) EtOH, wherein the proportions of (a), (b) and (d) in the total amount of (a), (b) and (d) are from 30 to 43 wt %, from 53 to 65 wt % and from 2 to 5 wt %, respectively. In composition Y of the present invention, preferred proportions of (a), (b) and (d) in the total amount of (a), (b) and (d) are from 40 to 43 wt %, from 53 to 57 wt % and from 2 to 4 wt %, respectively. More preferred proportions are 41.6 wt %, 55.1 wt % and 3.3 wt %, respectively. The composition wherein (a):(b):(d) =41.6:55.1:3.3 wt %, has a boiling point of 44.6xc2x0 C. under atmospheric pressure of 757 mmHg.
In the present invention, the azeotropic-like composition is meant for a composition whereby the difference in composition between the gas phase and the liquid phase is within 1% with R225, within 1% with t-DE and within 0.5% with EtOH, and the boiling point is within a range of 44.6xc2x10.1xc2x0 C. under atmospheric pressure of 757 mmHg.
Composition X of the present invention may contain the following compounds in addition to the above-mentioned (a), (b) and (c) in a range not to interfere with the first purpose of the present invention. Likewise, composition Y of the present invention may contain the following compounds in addition to the above-mentioned (a), (b) and (d) within a range not to interfere with the second object of the present invention.
Mainly for the purpose of controlling the solubility, one or more of the following compounds may be added to the compositions of the present invention within a range of from 0.1 to 50 wt %, preferably from 0.1 to 30 wt %, more preferably from 0.1 to 20 wt %.
Hydrocarbons such as n-pentane, 2-methybutane, 2,2-dimethylpropane, n-hexane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, n-heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane, n-octane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, cyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane.
Chlorinated hydrocarbons such as dichloromethane, cis-1,2-dichloroethylene, trichloroethylene, and tetrachloroethylene.
Ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone.
Ethers such as diethyl ether, methylcellusolve, tetrahydrofuran, and 1,4-dioxane.
Hydrochlorofluorocarbons such as 2,2-dichloro-1,1,1-trifluoroethane, and 1,1-dichloro-1-flouroethane.
Esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate.
Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, and t-butanol.
Mainly for the purpose of improving the stability, one or more of the following compounds may, for example, be incorporated to the compositions of the present invention with a range of from 0.001 to 10 wt %, preferably from 0.001 to 5 wt %.
Nitro compounds such as nitromethane, nitroethane, nitropropane, and nitrobenzene.
Amines such as diethylamine, triethylamine, i-propylamine, n-butylamine, and i-butylamine.
Phenols such as phenol, o-cresol, m-cresol, p-cresol, thymol, p-t-butylphenol, t-butylcatechol, catechol, isoeugenol, o-methoxyphenol, bisphenol A, isoamyl salicylate, bezyl salicylate, methyl salicylate, and 2,6-di-t-butyl-p-cresol.
Triazoles such as 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-3xe2x80x2-t-butyl-5xe2x80x2-methylphenyl)-5-chlorobenzotriazole, 1,2,3-benzotriazole, and 1 -[(N,N-bis-2-ethylhexyl)aminomethyl]benzotriazole.
Composition X of the present invention comprises R225, t-DE and MeOH in the specific proportions and thus is an excellent composition which presents no damage to the material of an article to be cleaned, such as plastics or rubbers, including e.g. rigid polyvinyl chloride, polystyrene, polycarbonate, polyphenylene oxide, ABS resin and EPDM elastomer, and which has nonflammability.
Composition Y of the present invention comprises R225, t-DE and EtOH in the specific proportions and is an azeotropic-like composition. Accordingly, it is an excellent composition which can be used with no substantial compositional change even when evaporated.
Further, the compositions of the present invention have a merit that they give little influence to the ozone layer, as the ozone depleting potential of R225 is about {fraction (1/25 )} of the ozone depleting potential of R113, i.e. while conventional R113 has an ozone depleting potential of 0.8, R225ca has a potential of 0.025, and R225cb has a potential of 0.33.
Further, the compositions of the present invention have a solvency substantially equivalent to conventional R113 or 1,1,1-trichloroethane, and thus they can be suitably used for various applications. Specific applications may, for example, include a cleaning agent for removing a soil such as grease, oil, flux, wax or ink from various soiled objects, a coating solvent, or an extracting agent. Further, they may be useful for a dust-removing agent for removing various dusts deposited on various articles made of glass, ceramics, plastics, elastomers or metals. Especially, they are suitable for a cleaning agent for removing various soils attached to articles such as ICs, electronic devices, precision machines and optical lenses.
They are particularly preferably used for a method of removing from an article, grease, oil or flux attached thereto.
As the cleaning method, manual wiping, dipping, spraying, shaking, ultrasonic cleaning, vapor degreasing or a combination thereof, may be used.